There has been "an alarming increase" in the number of working-age people suffering strokes, with unhealthy lifestyles being seen as the main cause.

The number of strokes occurring in those aged between 20 and 64 in England has gone up 25% since 2000, according to the Stroke Association in the UK.

But in men aged between 40 and 54, the increase is particularly alarming - up almost 50%. In women aged 40-54 the increase is 30% in England, while in Northern Ireland the number of strokes in men aged 40-54 has doubled, from 123 in 2002 to 252 last year.

The elderly are most at risk of suffering a stroke but the dramatic increase of occurrences in younger people is of particular concern to employers.

"There is an alarming increase in the numbers of people having a stroke in working age," said John Barrick from the Stroke Association.

"One of the major causes is high blood pressure and often that is something people do not realise they have.

"High blood pressure is associated with obesity, lack of exercise, increase in salt and bad diet plus all of the things we are told we mustn't do like smoking or drinking too much.

"We have seen an increase in many of those factors and we think that is now feeding through to the working age population."

The Stroke Association believes employers are not doing enough to help workers who have suffered a stroke.

Mr Barrick said: "Having a stroke is bad enough, but being written off by your employer through a lack of understanding can be catastrophic.

"Businesses play a crucial role in helping stroke survivors get back into the workplace and on the road to recovery. That's why we're calling on employers to be aware of the physical and emotional impact of stroke."

44-year-old banker Rebecca Nightingale was on her way out for the evening after a long day at work when she suffered a stroke on the London Underground - she had no idea that her blood pressure was high.

She told Sky News: "I just knew something wasn't quite right. I kept dropping my handbag and I couldn't use my right hand. I had no strength and must have dropped my bag at Waterloo about 3 or 4 times.

"You always think of it as being an old person's thing and I just thought 'it can't be a stroke. I am too young at 44'. As far as I was concerned, I had nothing else to make me think I had anything to worry about health-wise."

Rebecca has made a good recovery although often feels fatigued and suffers some numbness on the right side of her body. She has returned to work part-time.

"They [my employers] were obviously quite nervous about having me back because they did not know what to expect and I think this must be common.

"They have never had someone in their workforce who's ever had a stroke and they just didn't know what to do."